The present invention relates to electrical triggering devices, and more particularly to transducers for synchronizing external equipment with acoustic devices such as musical instruments and the like.
Triggering devices for use with musical instruments are known, being disclosed, for example, in U.S. Pat. Nos. 5,036,742 to Youakim, and 5,134,920 to Clark. Many such triggering devices of the prior art have a piezoelectric transducer element in facing contact with an acoustic member such as a drumhead, the element being pressed against the acoustic member by a foam pad that is clamped by a rigid supporting structure, the structure being anchored to a stationary member such as a drum clamp ring.
Triggering devices for musical instruments are subject to a number of disadvantages, including undesired dampening of the natural sound of the instrument, marginal signal amplitude for effective and uniform triggering, and frequency response that is incompatible with reliable response to fundamental sound frequencies that are produced by the particular instrument. When several instruments are being played it is commonly desired to trigger external equipment from drums, because it is customary to synchronize the playing of the other instruments being played to drum beats. Thus many trigger applications are for drum triggers.
Drum triggers of the prior art include those having a transducer element such as a piezoelectric device in direct contact with the drum head, and those having the transducer device isolated from the head by a resilient material such as foam rubber. Prior art triggers having full face contact between a piezoelectric element (or its adjacent support structure) and the drum head typically make contact with 0.3 square inches or more of the head, resulting in undesirable dampening or muffling of the drum. Also, high frequency components of the output signal having significant amplitude are undesirably out of phase with fundamental components, resulting in faulty trigger timing. Triggers having edge contact with the piezoelectric element have been introduced, but these exhibit inadequate excitation of the element with respect to both the amplitude and shape of the output waveform.
The prior art examples having the resilient material between the element and the head produce excessively low output amplitude unless the contact area and/or pressure is unacceptably high.
Thus there is a need for an acoustic triggering device for electronic equipment that provides high output amplitude without excessive muffling or dampening of the acoustic source, that does not produce faulty timing as a result of high frequency signal components, that is easy to use with a variety of acoustic sources, and is inexpensive to provide.